The Dark Side Of Light

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Light Pollution is proving fatal to birds and other wildlife.

Leaving the lights on is more expensive than you'd think. It not
only costs a chunk of change, but it also takes a surprising toll
on the environment. The proliferation of artificial lighting threatens
wildlife, ruins habitat, fouls the air, squanders resources, and
blocks our view of the heavens. No wonder the pervasive problem
has come to be called light pollution.

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Astronomers were the first to notice this problem. About 30 years
ago they began to be frustrated as sky glow, the eerie radiance
that emanates from settled areas and has spread with urban sprawl,
began impairing their ability to see the stars. Today as few as
one in 10 Americans live in areas where they can see the 2,500 or
more stars that should be visible under normal nighttime conditions.
In most big cities, you're lucky to glimpse a few dozen - on a good
night.

But light pollution isn't just an urban problem. In Springfield,
Vermont, a controversy has erupted over the economically depressed
town's decision to permit the construction of a prison; the lights
from the site, it is feared, would mar the view from Breezy Hill,
of of New England's best places for stargazing. Each year since
1926, thousands have flocked to Breezy Hill for a celebration of
the stars called "Stellafane." David Levy, an astronomer,
has led the protest against the proposed prison. "Stellafane
is a magical place, a sanctuary to the stars," he wrote in
"Sky & Telescope" magazine.

Although light pollution's impact on stargazing is as clear as
day, its effects on other environmental elements are just coming
into focus. The evidence shows that artificial lighting has direct
consequences for animal behavior, particularly on the ability to
navigate at night. The hundreds of species of migrating birds that
fly after the sun sets, including most songbirds and many shorebirds,
are prime examples.

Normally they rely on constellations to guide them during their
twice-yearly migrations. But scientists speculate that when they
fly near urban areas, the bright lights short-circuit their steering
sense. Numerous reports have documented birds flying off course
toward lights on buildings, towers, lighthouses, even boats. "Both
birds and insects demonstrate positive phototaxis," says Sidney
Gauthreaux, a Clemson University biologist. "To put it simply,
birds are attracted to light much like moths are to a flame. But
the reasons are unclear. They may use it as a reference and home
in on it." When birds suddenly reach the light's source, they
often seem to become confused or blinded by the glare, which can
be disastrous.

Birds may slam into windows, walls, floodlights, or even the ground.
On the night of October 7, 1954, for instance, 50,000 birds were
killed when they followed the beam of a guide light at Warner Robins
Air Force Base in Georgia - straight into the ground. The problem
is particularly acute when the weather is bad. On a rainy, foggy
Labor Day weekend in 1981, more than 10,000 birds collided with
the floodlit smokestacks at Ontario's Hydro Lennox Generating Station,
near Kingston. And on January 22, 1998, between 5,000 and 10,000
Lapland longspurs crashed into radio transmission towers near Syracuse,
Kansas.

Birds that are distracted by tower lights also may end up crashing
into one another. "Around communication towers with constant
lights, birds curve, circle, pause, and hover around the lights,"
Gauthreaux explains. They are apparently trying to orient their
flight to the light, which they mistake for the moon or a star.
"Over time there's buildup of migrants [all trying to adjust
their course], raising the possibility of hitting guylines or other
birds." Nobody is certain of the total number killed across
North America, but Michael Mesure of the Fatal Light Awareness Program
(FLAP), a Toronto organization working to publicize the problem,
estimates that at least 100 million birds are killed annually by
manmade structures. "More birds die each year through collision
than dies in the Exxon Valdrex spill," he says. A tall building
in the path of a migration can claim hundred of lives. One example:
From 1982 to 1996, 1,500 migrating birds have smacked into Chicago's
McCormick Place Exposition Center.

Although few nocturnal migrants seem immume to light's dark side
- for example, dead or injured members of 141 different bird species
have been found at McCormick Place - songbirds may be most at risk,
Mesure says, because they fly at low altitudes dominated by artificial
light. Passerines are not the only order of birds waylaid by lights.
The Newell's shearwater, an endangered Hawaiian seabird, is particularly
vulnerable.

After their parents abandon their cliffside nests in October and
November, fledglings make their first flights by relying on their
innate attraction to light to guide them. Normally, because of the
light's reflection on water, they fly out to sea, toward the horizon.
But when the moon is neither full nor visible, many of the shearwaters
instead glide toward lights in seaside resorts and towns. Disoriented,
hundreds crash into structures or drop from the sky. In 1998 volunteers
gathered 819 shearwaters on the island of Kauai. Most were exhausted
or injured, though fortunately, only 77 died.

Other animals are threated by light pollution, too. Hatchlings of
at least five sea-turtle species found in Florida rely on an instinctive
attraction to light to guide them to water. But lights on or near
the beach can confuse the turtles and cause them to head in the
wrong direction. Scientists have seen hatchlings cross parking lots,
streets, and yards - transfixed by shining streetlights or porch
lights. "Their reliance on light is so strong that they'll
continue heading to a light source, even if it's an abandoned fire
that burns them alive," says Blair Witherington, a Florida
Marine Research Institute scientist who studies sea turtles. Disoriented
hatchlings usually die from exhaustion, dehydration, or predation.
Many others are squashed by cars.

Insects cannot seem to resist this fatal attration either. Most
people know that moths find lights irrestible. But what they may
not realize is that the energy moths expend in this way can cost
females the chance to attract a mate. What's more, it can interfere
with locating prime spots to lay their eggs, thus giving larvae
inadequate conditions to develop, according to Michael Collins,
a lepidopterist at the Carnegie Museum. Some entromologists speculate
that the proliferation of outdoor lights has contributed to the
decline of numerous saturniid moth species in the northeastern United
States.

Visual orientation is just one sense disrupted by artificial light,
though it probably isn't the only one, says Meredith West, an Indiana
University professor specializing in avian development. Studies
of animals raised in controlled settings, like laboratories and
poultry farms, indicate that lighting can affect certain "photo-periodic"
behavior, including foraging and reproduction.

"Animals are very sensitive to light," West says. "Lighting
is a powerful stimulus on behavior. If there's enough of it, it
can make them act in ways they wouldn't normally." If enough
light is present - say, in a well-lit neighborhood - it's possible
that animals living there would be stimulated to act as they do
during longer days. Overexposure to light may explain reports from
English researchers about robins singing at night if there are streetlights
in their territories, or why some birds build nests during the fall,
instead of spring: Their internal clocks have gone haywire. Adult
female sea turtles will not emerge from the water to next and lay
eggs on beaches that are bathed in artificial light. Many behaviors
influenced by changing light - from night to day and the seasonal
increases of longer days - involve hormones. "Anything that
alters the hormonal system will bring enormous changes," West
says. "Hormones regulate growth and immune functions. But they're
not produced all the time. If they don't shut down, you overload
the body. It can't get rid of them. Hormones are toxic in the wrong
amounts."

Even if wildlife were able to ignore direct sources of light,
lighting's impact on the environment would still be unavoidable.
Burning coal and oil, according to the Environmental Protection
Agency, generates most of the electricity for lights. The process
is a dirty one that each eyar spews out billions of tons of carbon
dioxide, a greenhouse gas; sulfur dioxide, an ingredient of acid
rain; and nitrogen oxides, which cause smog. Sadnly, much of this
atmospheric pollution is produced for nothing. "One-third of
our lighting is wasted because it shines upward or sideways, illuminating
nothing but the bottoms of birds and airplanes," says David
L. Crawford of the International Darksky Assocation (IDA), a 10-year
old anti-light-pollution group based in Tucson. Every year this
waste squanders the equivalent of 8.2 million tons of coal or 30
million barrels of oil.

Of course, using less energy would reduce emissions. In addition,
research in toronto and Washington D.C. shows that when building
lights are dimmed or turned off, thenumber of fatally attracted
birds drop dramatically. "If you have a tower without lights,
you'll cause bird collisions, but at least you won't be attracting
more birds to it," Gauthreaux says. The challenge for the government
and environmental groups it to, no pun intended, enlighten people.
The Environmental Protection Agency has created an energy-saving
program, Energy Star, to help companies and residents reduce lighting
use. Several manufacturers have begun producing energy-efficient
lights and appliances.

FLAP launched a 12-step bird-friendly program that encourages buildings
to turn down lights during migrations; it has been adopted at 100
buildings in downtown Toronto since 1997. FLAP organizers are leading
similar efforts to raise awareness in Chicago and New York. Any
educational drives to publicize the impact of light on turtle hatchlings
and seabird fledglings are now being sponsored by the National Park
Service in Hawaii and by county governments in Florida.

Some cities, including Tuscon and Miami, are replacin innefficient
streetlights with ones designed to focus the beam more sharply.
In addition, last August two workshops at the Americal Ornithologists
Union conference explored light pollution's impact on birds.

Meanwhile, lawmakers in hundreds of communities have passed ordinances
that restrict lighting types, power, and use. Last spring Texas
and New Mexico became the fourth and fifth states (along with Arizona,
Connecticut, and Maine) to implement a statewide light-restriction
program. The ordinances vary in scope, from banning certain types
of streetlights or limiting their wattage to shielding security
lights. Similar actions are being considered in other states.

Any dark-sky proponest will admist that the national impact of
these programs is minimal. But Crawford of the International Dark-Sky
Assocation believes that they're a good start. "All the evidence
shows it's bad, but we have to educate people about the consequences.
Smoking bans are coming quickly now, but the education that brought
them about took a long time."